In recent years, increasing amounts of radioactive waste are generated from nuclear power facilities such as nuclear power plants, and medical facilities, universities and laboratories that use radioisotopes. Accordingly, a reliable measure for radioprotection is demanded.
Further, it is said that miners in mines of uranium ore, coal or metals are exposed to more than 6 times as much radiation from the earth's crust as allowed by international recommendations for radiation workers. Moreover, the amount of radiation from outer space (cosmic rays) to which flight crews are said to be exposed is much greater than that to which miners are exposed. A solution of these problems is urgently required.
Besides these specific facilities, luminous paints on clock or watch faces, glow lamps in fluorescent lamp devices, discharge tubes in displays in gas stations or the like, and smoke detectors in buildings employ isotopes that emit alpha rays or beta rays. Therefore, proper radiation control is always necessary in production sites of these items.
“Radiations”, in a broad sense, include cosmic rays, radio waves, infrared radiation, visible light, Ultraviolet-A, Ultraviolet-B, Ultraviolet-C, directly ionizing alpha rays, beta rays, proton beams and baryon beams, indirectly ionizing X rays, gamma rays, electron beams and neutron beams, etc.
Among these radiations, Ultraviolet-A, Ultraviolet-B, directly ionizing alpha rays, beta rays, proton beams and baryon beams and indirectly ionizing X rays, gamma rays, electron beams and neutron beams necessitate radioprotection.
For protecting the internal or external (such as the skin, hair, eyes or the like) parts of the body from ultraviolet rays, sunglasses with large, light-colored lens, hats with all-around brims with a width of at least 7 cm, dark-colored clothes made of polyester fibers or hemp fibers, ultraviolet blocking cosmetics containing titanium oxide are reportedly effective. However, these means block only Ultraviolet-B, which, for instance, damages DNA in the epidermis of the body, promotes the formation of melanin pigment, rapidly increases active oxygen and thereby ages the tissue cells of the epidermis, and causes skin spots. On the other hand, Ultraviolet-C reaching the earth has been greatly increasing in recent years owing to the destruction of the ozone layer, and thus the effects of Ultraviolet-C pose problems. Further, it is known that Ultraviolet-A penetrates deep into the dermis of the body and cuts or destroys elastic fibers to thereby form unremovable wrinkles or cause cataracts. Thus, protection means against these ultraviolet rays are also hoped for.
Moreover, exposure to alpha rays, beta rays, X rays, gamma rays or like ionizing radiation which permeates the human body not only causes acute disorders of the body, including those of the blood and organs, but also has long-term averse effects on the human body, such as carcinogenesis, genetic damage or the like. Development of a protective material against these radiations is desired, in order to ensure radioprotection for people in general, as well as people who work with radiation and nuclear power.